| Abstract: | Functional MRI (fMRI) resting-state experiments are aimed at identifying brain
networks that support basal brain function. Although most investigators consider
a ‘resting-state’ fMRI experiment with no specific external stimulation,
subjects are unavoidably under heavy acoustic noise produced by the equipment.
In the present study, we evaluated the influence of auditory input on the
resting-state networks (RSNs). Twenty-two healthy subjects were scanned using
two similar echo-planar imaging sequences in the same 3T MRI scanner: a default
pulse sequence and a reduced “silent” pulse sequence. Experimental sessions
consisted of two consecutive 7-min runs with noise conditions (default or
silent) counterbalanced across subjects. A self-organizing group independent
component analysis was applied to fMRI data in order to recognize the RSNs. The
insula, left middle frontal gyrus and right precentral and left inferior
parietal lobules showed significant differences in the voxel-wise comparison
between RSNs depending on noise condition. In the presence of low-level noise,
these areas Granger-cause oscillations in RSNs with cognitive implications
(dorsal attention and entorhinal), while during high noise acquisition, these
connectivities are reduced or inverted. Applying low noise MR acquisitions in
research may allow the detection of subtle differences of the RSNs, with
implications in experimental planning for resting-state studies, data analysis,
and ergonomic factors. |
